Apparatus for bulk curing tobacco



Oct. 1, 1963 F. J. HASSLER 3,105,713

APPARATUS FOR BULK CURING TOBACCO Filed June 13, 1960 2 Sheets-Sheet 1 IIIWWWWJW JIE. 9

Oct. 1, 1963 F. J. HASSLER APPARATUS FOR BULK CURING TOBACCO 2 Sheets-Sheet 2 Filed June 13. 196'.

INVENTOR. FmA/c/s J, MSSA 2 BY 4i HIS qrroeusvs United States Patent 3,105,713 AFPARATUS FOR BULK URING TOBACCO Francis J. Hassler, Raleigh, N.C., assignor, by mesne assignments, to R. H. Bouligny, Inc, Charlotte, N.C., a corporation of North Carolina Filed June 13, 1960, Ser. No. 35,499 1 Claim. (Cl. 245.5)

The present invention relates to an improved method and apparatus for curing tobacco and, more particularly, to a method for curing tobacco in bulk and the apparatus for carrying out such method, however, the invention is not necessarily so limited.

A fundamental problem in tobacco production is the great amount of hand labor required in the conventional method of production. Approximately three-fourths of the total labor required in the production of tobacco is devoted to harvesting and processing operations. In recent'years much has been done in the way of mechanizmg harvesting operations, and the labor saving through mechanization has been substantial. However, there has been little advance in the techniques for processing the harvested tobacco. Thus, the techniques for processing tobacco today are, with the exception of a few minor improvements, the same as employed more than a century ago.

In curing tobacco it has long been the practice to string the tobacco leaves on elongated sticks which are supported in a curing barn. The stringing operation is a cumbersome and time consuming operation which must be done by hand. When the tobacco has been strung and placed in the barn, it is carried through a curing operation which can be roughly divided into four stages.

These stages will be described in detail in the following remarks. Accordingly, it suflices for the present to state that the first stage is a leaf yellowing stage wherein physiological transformations evidenced by yellowing of the tobacco leaf occur. In the second stage the leaf is dehydrated to halt the physiological transformations occurring in the leaf. In the third stage the dehydration is accelerated so that the stem of the tobacco leaf is dried out. At this point, the tobacco leaf is substantially bone dry and the leaf itself is very fragile. In the final stage moisture is added to the leaf so that it softens and can be handled. Thereafter, the tobacco is ready for removal from the curing barn for subsequent processing.

It is obvious that the curing of tobacco could be greatly simplified if it were possible to cure the tobacco in bulk. This would eliminate the cumbersome stringing operation since it would then be possible to cure the tobacco in large bundles. Unfortunately, however, the leaf yellowing stage described above involves exothermic reactions in the tobacco leaf. Thus, when tobacco is cured in bundles, large amounts of heat must be dissipated. For this reason, it has been considered impossible to satisfactorily control a bulk curing operation.

It is an object of the present invention to provide a method for curing tobacco which enables bulk curing and which affords sufficient control'over the curing process that the heat released exothermically does not impair the operation.

' Another object to the present invention is to provide apparatus for bulk curing tobacco, which apparatus enables close control over heat released during the curing operation.

Still another object of this invention is to provide an improved method for bulking tobacco in racks.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufac-' ture and the mode of operation, as will become more apparent from the following description.

FIGURE 1 is a perspective view of the tobacco curing barn.

FIGURE 2. is an end elevational view of the barn taken from the direction indicated by the arrows 22 of FIGURE 1.

FIGURE 3 is a sectional view of the barn taken sub stantially along the lines 33 of FIGURE FIGURE 4 is a plan view of the interior of the barn.

FIGURE 5 is a longitudinal sectional view of the barn illustrating heating apparatus employed therein.

FIGURE 6 is a perspective view illustrating the method of placing tobacco leaves in a rack.

FIGURE 7 is a perspective view illustrating a completed rack of tobacco.

FIGURE 8 is a fragmentary plan view of an assembled rack with the tobacco removed.

FIGURE 9 is an end view taken in the direction of the arrow 9-9 of FIGURE 8.

Referring to the drawings in greater detail, FIGURE 1 illustrates a tobacco barn 10 which is designed specifically for use in the present method. The exterior covering for the barn is formed with a plurality of arched sheet metal panels 11. At the forward end of the barn, as viewed in FIGURE 1, an overhang 12 is provided. This overhang provides a shelter where tobacco leaves may be placed in racks, as will be described hereinafter, prior to movement into the curing barn. Behind the overhang 12 is a partition 14 which closes the forward end of the barn. As best illustrated in FIG- URE 2, this partition includes three doors 14a, 14b and 14c which may be opened to gain access to three separate compartments within the barn.

Rearward of the partition 14 is another partition 16 which cooperates with a rear end wall 18 to establish a furnace room. The partition 16 isolates the furnace room from the central part of the barn.

As best seen in FIGURE 3, the central part of the barn is divided into three sections by a pair of dividers 20a and 20b extending between the partitions '14 and 16. The doors 14a and '14b and 14c open separately into these sections.

The dividers 20a and 20b, as well as the side walls of the barn, support horizontal rails 22 which form supporting shelves for tobacco racks placed thereon. [FIG- URE 3 schematically illustrates tobacco cracks or supporting frames 24 supporting tobacco leaves 26 mounted on the rails 22. In the tobacco barn illustrated, two tiers of tobacco racks are placed in each of the three sections of the barn.

FIGURES 4 and 5 illustrate a heating system which is installed in the barn. This system includes a furnace 30 located in the furnace room between the partition 16 and the end wall 18. Leading from the furnace at floor level are three outlet ducts 36a, 36b and 360, each of which is regulated by a hand damper 34. These three ducts pass centrally through the three sections of the central portion of the barn and are each provided with a plurality of spaced openings or ports 38 in the sides thereof through which air may escape. A blower unit 32 located within the furnace forces air into the duct 36. The air leaving the ports 38 moves upwardly between the bulked tobacco leaves and ultimately flows into a return duct 40 located centrally in the barn at an elevation above the dividers 20a and 20b. This duct 40 is provided with spaced ports 42 into which the air moves.

A damper 44 is located in the duct 40 between the several ports 42 and the blower 32. Above the damper is an outlet duct 46, best seen in FIGURE 4, communicating with the outside atmosphere. By adjustment of the damper 44, varying amounts of fresh air may be admitted to the heating system, or if desired, the duct 46 may be closed such that the air within the system is recirculated without addition of fresh air.

The blower 32 operates to establish a pressure differential between the top and bottom of the curing barn in the central curing section such that the air is forced to move upwardly through the tobacco. The design of the racks is such as to force the circulated air to flow between the bulked tobacco leaves.

An individual rack 24 is illustrated in FIGURES 8 and 9. This rack includes an elongate side member 50 with outwardly extending rods 52 fixedly secured to each end thereof. A second side member 54 of equal length has apertures 53 therein complementary to the rods 52, the arrangement being such that the rods 52 may be projected into the apertures 53 to assemble the rack. Suitable nuts 55 are threaded onto the rods 52 to fix the assembly. The side member 54 carries a plurality of parallel fixedly attached spikes 56 which, in theassembled rack, abut a shoulder 58 provided on the side member 50.

'In bulking tobacco, the rack is used in association with a bin 60 illustrated in FIGURE 6. This bin has an open top and one open side. The end walls 62 of the bin are hingedly joined to the rear panel 63 and are normally locked in the position illustrated in solid line detail. In inserting the tobacco into the rack, the side member 50 is seated on the bottom of the bin and is located by slots 64 provided in the end walls 62. The rods 52 carried by the side member 50 project upwardly in the slots 64. The bin 60 is then filled with tobacco leaves each of which has its base butted against the rear panel 63. The side member 54 is then pressed downwardly into the bin 60 to force the spikes 56 through the tobacco leaves. Any suitablydesigned press mechanism may be employed to force the side member 54 into the bin 60 in accurate registry with the side member 50.

After the side member 54 has been forced into the bin 60 and secured by means of nuts 55 engaging the rods 52, the end walls 62 are swung outwardly so that the rack may be removed from the bin. A completed rack of tobacco is illustrated in FIGURE 7. In the completed rack, the shoulder 58 provided on the side member 50 supports the ends of the spikes 56 so that the weight of the tobacco does not deform the spikes.

In loading the racks in the curing barn the racks are slid along the rails 22 and pushed one after the other into the barn. The dimensions of the racks are modular with respect to the interior of the barn so that when a full complement of racks are b-utted one against the other, they exactly fit between the partitions 14 and 16 leaving substantially no room for escape of air around the sides of the racks. In this regard it will be noted in FIGURE 3 that the leaves of the tobacco flare outwardly from the racks and cooperate withthe rails 22 to minimize the escape of air around the ends of the racks. The air which is forced upwardly through the central portion of the barn must therefore move in and around the tobacco leaves.

As mentioned hereinbefore, the initial portion of the tobacco curing cycle involves exothermic reactions and it is important that the temperature of the tobacco leaves be carefully controlled during this portionof the cycle. This is done by forcing air of the correct temperature and humidity through the tobacco.

At the beginning of the curing process, the tobacco leaf contains complex starch and protein molecules, chlorophyll, nicotine, water and many other components. The leaf moisture content is normally 80 to 90 percent of the total green weight of the leaf. In the initial curing stage, designated the leaf yellowing stage, the major chemical conversions are the simplification of complex starch and protein molecules and the disappearance of chlorophyll by oxidation. Rapid dessication at this stage would arrest all chemical conversions and accordingly the moisture content of the leaves must be maintained above 70 percent. During this stage, starch molecules i to 60 hours depending upon the state of the'leav'es when the cure is begun. During this period, the moistur are hydrolyzed to simpler sugars. The disappearance of chlorophyll proceeds at a rate parallel to the conversion of starch. Thus, the leaf color is a good indication of the state of the leaf. When'all chlorophyll has disappeared the major portion of the starch has been hydrolized. This is evidenced by a yellowing'of the leaf as the disappearing chlorophyll unmasks yellow leaf pig-i ments. a

The rate at which the aforementioned reactions occur increases with an increase in temperature. cure time is shortened with increasing temperature. However when the temperature exceeds R, an undesirable browning resulting from oxidation of polyphenols occurs, along with other reactions which result in an accumulation of undesirable components. Under the cir-' content of the leaf reduces to about 70 or 75%.

After yellowing is accomplished, that is, after the leaf is at the desired chemical state, further chemicalreaction is arrested by dehydrating the leaf. This stage of the cure process is known as the leaf drying stage. To accomplish dehydration, the air temperature is elevated at a rate of 2 to 3 F. per hour and is ultimately held in the range of to F. To insure maximum dessication, the dampers. are adjusted to exhaust the humid air with no recirculation. The normal time required for the leaf drying stage is from 20 to 30 hours during which the leaf moisture content is reduced to a level of 30 to 50%. With average atmospheric conditions the air circulated through brittle while the moisture content of the leaf lamina ap proaches zero. The leaf becomes crisp and fragile in this stage and it is necessary to recondition or reorder the leaf before removal from the curing bann.

In the final stage of the tobacco cure, moisture is added This may be accomplished in two ways.

to the leaf. Under favorable environmental conditions of 50' i070 F. and 85 to 100% (relative humidity, air can be drawn 7 in from outside the barn and forced through the tobacco without additional heat, then exhausted from the. barn.

However, when the ambient atmosphere is not sufficiently humid it is fcundpreferable to employ a humidifier,- not shown, located within the duct work. The controls are set to provide a temperature of from 80 to 100 F. and a relative humidity ofaround 85% with full recirculation e of air. Normally the leaf is conditioned to a moisture content of 15 to 20% :by weight. The time required for i this reconditioning is 6 to 10 hours. The tobacco is then ready for removal from the curing barn.

.It is found that bulk curing on the cycle indicated produces a marketable tobacco leaf comparable to the best obtained with conventional curing techniques.

the same time, it is found that the cure obtained is more uni-form than that obtained conventionally such that a higher average market price is realized. Another important advantage resulting from the method and apparatus disclosed herein is a substantial. reduction in amount of labor required to effect the cure;

Although the preferred embodiment of this method:

Hence, the

the

and apparatus has been described, it will be understood that within the purview of this invention various changes may be made in the norm, details, proportion and arrangement of parts, the combination thereof, the method of manufacture and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claim.

Having thus described my invention I claim:

A rack for supporting a batch of tobacco leaves in compressed bulk form within a curing barn for passage of a flow 'of forced air vertically therethrough comprising a pair of separable rack sections disposed in spaced relation with respect to each other in a loading position with a batch of tobacco leaves in loose bulk form having the flat surfaces thereof disposed generally in the same direction positioned therebetween, a plurality of thin elongated spikes fixedly secured at one of their ends to one of said rack sections in generally parallel relation and extending in a direction toward the other of said rack sections when the latter are disposed in said loading position, said rack sections being movable with respect to each other from said loading position rectilinearly toward each other in the direction of extent of said spikes into an operatively engaged position to pierce the free ends of said spikes into the leaves in a direction perpendicular to at least a substantial portion of the flat surfaces thereof and to compress the batch of leaves in loose bulk form into a relatively compact batch on said spikes, and means carried by said rack sections adjacent each of the end portions thereof engageable to fixedly secure said rack sections against movement out of said operatively engaged position after the rectilinear movement of said rack sections into said operatively engaged position and disengageable to permit movement of said rack sections out of said operatively engaged position, said rack With said rack sections in operatively engaged position providing a rectangular structure defining a continuous inwardly facing peripheral surface means for exteriorly peripherally supporting the batch of compressed leaves, spaced supporting surfaces on one pair of opposite sides thereof facing in a direction perpendicular to the direction of extent of said spikes for engagement with cooperating oppositely facing supporting surfaces in the curing barn to mount the rack in an openatively engaged curing position within the curing barn for passage of the flow of forced air vertically through the batch of leaves supported therein with their fiat surfaces extending generally in the direction of the forced air flow, and exterior outwardly facing surfaces extending along the other pair of opposite sides thereof each being of a configuration to engage a corresponding opposite exterior surface of a similar rack in operatively abutting relation along the entire length of the respective exterior outwardly facing surfaces so as to effectively prevent the passage of air therebetween when such racks are disposed in operatively engaged curing position in side-by-side abutting relation, said spikeswhen said rack sections are disposed in said operatively engaged curing position extending generally horizontally substantially throughout the space Within which the batch of leaves is peripherally confined by said continuous peripheral surface means and being spaced apart relative to each other a distance substantially greater than their thickness and substantially less than their length so as to provide adequate interior support for the batch of leaves without materially restricting the fi-ow of forced air vertically through the batch of leaves.

References Cited in the file of this patent UNITED STATES PATENTS 216,293 Robinson June 10, 1879 882,474 Lott Mar. 17, 1908 912,902 Sharon Feb 16, 1909 1,322,648 Sullivan Nov. 25, 1919 1,521,083 Edwards Dec. 30, 1924 1,522,489 Bolen Jan. 13, 1925 2,121,370 Touton June 21, 1938 2,182,753 Crane et a1 Dec. 5, 1939 2,434,309 Broughton Jan. 13, 1948 2,708,441 Viglione May 17, 1955 2,798,496 Jones July 9, 1957 2,808,283 Vickers Oct. 1, 1957 2,369,556 Rowell Jan. "20, 1959 OTHER REFERENCES News and Observer, Raleigh, North Carolina, page 15, Monday Morning, November 10, 1958. 

